Selective signaling apparatus and circuits



April .28, 1925.

J. F. TOOMEY SELECTIVE SIGNALING APPARATUS AND CIRCUITS Filed Oct. 10, 1919 3 heet 1 INVENTOR J17 @Wlfli' BY ATTORNEY J. F. TOOMEY- SELECTIVE SIGNALING APPARATUS AND CIRCUITS April 28, 1925.

Filed 000. 10, 1919 SSbeets-Sheet 2 INVENTOIf. (M mi A TTORNEY April 28, 1925.

J. F. TOOMEY SELECTIVE SIGNALING APPARATUS AND CIRCUITS s Sheet-Sheet 5 Filed Oct. 10, 1919 IN VEN TOR.

Q. ATTORNEY Patented Apn zt', 1925.

outrun stares .romv r. TOOMEY, or new YORK; N. r,

ASSIGNOR; TO AMERICAN TEBEPHUNE AND TELEGRAPH COMPANY, A GORPQRATIQN OF NEW YORK.

SELECTIVE SIGNALING AIPiPARATUS AND CIRCUITS.

Application filed. October. 10, 1919, Serial no. 329,802.

ing; apparatus and circuits; and is described herein in connection with a selective ringing arrangementv for" a telephone system, it being readily understood that it is not thus limited in use but applicableto other electrical systems.

The arrangementot this invention provides for selective signaling over a telephone line by the use of ringing; currents differing in duration' Apparatus is provided at each ofiice. associated with a line. whereby only one of the several operat-ors positions associatedwith the line is caused to. receive an incoming call signal according to the length of the ring; this apparatus being arranged also to send out ringing currents of various duration so that the operators may signal selectively-to the positions at other oflic'es associated with the line.

A good understanding; of the invention. may be had from the a following; description thereof, reference being had tothe accompanyingidrawings in which Fig. 1 is a diagrammatic View of one form of signal send ing and receiving): circuits embodying the in vention; Fig'. 2 is a view similar to Fig. 1 showing one modification of? the signal sending circuits; andFig. 3 is a view showing another modification of the signal sending circuits. 7 7

Similar characters of reference designate similar parts in each of the several views.

In Fig. 1 of the drawings. reference character Z designates a long distance telephone linewhich is associated by means of a re lay Owith switchboard conductors 2 and 4;. Jacks 1, 3 and 5 have their tip and ring; contracts bridged across the switchboard conductors. these jacks corresponding respectively to the inwardQoutward andthrough operators" positions. Signaling or answerinp: lamps 1 3 and 5 are provided adjacent the above mentioned i aclzs for indicatin incoming calls, and busy signals 1",?5 and 5 areemployed for indicating; at each position whether or not the line is busy. Apparatus i provided. for selecting only one of the ansavoring lamps 13,3? and 5 to respond to a ring coming in, on line Z according to the length of the ring, this apparatus comprising a circuit controller Y, which is fully described in my copendinp; application for patent, on circuit controllers Serial No. 329,801 filed of even date herewith. The controller comp 'iscs, briefly, a motor having an armature designated D and a field not shown in the drawing, which motor rotates a disk 7 of magnetic material, by means of worm gearing 6. A contact arm 8, also of magnetic material. is mounted loosely on the shaft of disk 7 and provided with; a magnetizing winding 9 which. when energized, causes the arm to move into engaflze ment with the disk and rotate therewith. Au insulated contact brush 10 at the eratremity of arm 8 is provided to bridge con tact points, certain of which are designated in the drawing by reference characters 1. 3 5 and 1, 3 and 5. Brush 10 operates these contacts consecutively in clockwise or counterclockwise order according to the direction of rotation of motor D; and the time interval which elapses between the time when the motor begins to operate and the time when the brush reaches one of the contact points, is fined and easily able, being determined by the ang e tance of the contact point from the initial position of the Contact "When the magnetizing winding 9 is deenero iaed. the

arm 8 is forced away from the dish '3 by means of a spring (not shown in the drawings); so that the arm falls baclr to its initial positionwithout operating the contacts during its return movement. Further description of the various features of this circuitcontroller may be had by reference to my above mentioned copending application. Z

The operation of the circuits of this invention is as follows: hen ringing current is applied to line Z at; a distant oliice not shown in the drawings, the current flows over the line into switchboard conductors i2 and 4e, and operates the relay A which is bridged across the switchboard conductors through the normally closed back contact of a'relay J. Relay A closes the circuit of relay B and causes the same to apply ground to the circuit of a relay C. This relay operates and causes current to flow over its contact 12 and wire 13 through the Qil busy signals 1, 3 and 5 in series, thus indicating immediately that the line is in use. Relay C also causes current to flow over its front contact 14-, through contact 15 of relay 1, wires 16 and 17, through the magnetizing winding 9 and through the frame of the controller to ground, thus energizing this winding and causing the arm to revolve with the wheel 7 which is now being rotated in clockwise direction by motor D, the armature circuit of. which is in parallel with winding 9. extending through wire 18 and the back contact 19 of a relay P. through the motor armature and back contact 20 of relay P to ground. The circuit controller Y is thus caused to begin to operate the moment the operator at the distant oliice applies ringing current to the line.

Relays A and B remain operated only as long as the signaling current continues to come in over the line. As soon as the current ceases, relay I) applies erounid to the wire 21, which is connected over the back contact 22 ot relay N and through a wire 24 to the inside contact points of the circuit controller Y. H the duration ot the ringing current is, say, one second. and it the time it takes for contact brush 10 of the controller to reach the contact point 1 is also one second. the above described connection of ground to the inside contact points of the controller will take place at the time when the brush .10 is bridging the contact points 1. so that current flows for a short interval of time from a battery 25. through the back contact of relay J. wire 28, windings of relay l and F in series through contact point 1 to ground at relay Relays F and I are thus energized and lock up through the armature 26 ot'relay F. which is connected to ground. Relay F closes at contact 2'? the circuit ot the an swering' lamp 1. so that current flows therethrough from batter over the hack con- "act of sleeve relay J. through wires and. 29. front contact 27 of relay F and wire 30 through the filament of the lamp 1". A. ring of one second duration causes thus the response of the inward. answering lamp. The relay 1 which, as before noted. is locked up through the contact 26 of relay F. opens at contact 15 the circuit of motor l) and magnetizing winding 9 so that the circuit controller ceases to operate, and arm 8 returns to its initial position. The relay C, which is of the slow release type, opens its contacts shortly after relay B becomes deenergized, and the busy signals which were previously supplied with current through the contact 12 of relay (l. as hereinbefore noted, are now energized by current from battery 25 flowing over the back contact of relay (l. through conductor 28, contact 32 of relay 1 and wire 13. The lamp 1, the busy signals, and relays F and I, are thus maintained energized, the remainder of the apparatus having been returned to its normal inoperative position.

l Jhen the inward operator answers by inserting the plug of her cord circuit into jack 1, she causes current from the sleeve battery .2 of the plug' to energize relay J, the circuit which is in series with a marginal relay 1, the purpose of which is described here nutter, it being;- suliicient to note for the nesent that the current from battery 4-2 is nsuiiicient to energize relay L. The relay J opens its back contacts and thus dcener gizes relays F and I, so that lamp 1 is cxtinp'uished. The busy signals. however. remain energized by current from battery 25 through the -trout contact of the sleeve relay J. l i hcn, finally, the operator ta down the connection, she breaks the oi: oi"- relay J and thus causes the deenergizati on ot the busy signals, so that all of the apparatus is again restored to the normal inoperative position she tn in the drawing.

When the incoming signaling current is of a duration longer than one second. say three seconds, relay B is not dcenergrizcd until the b ush it) of the controller Y is in engagement with the contact points 53. so that in this case the relays and I are operated instead or relays F and I. relay being in parallel with relay F. but connected to contact point 3. The energization of relay G causes the closure at contact 34 of the circuit of the answering lamp 3. so tha the outward operate-W's position receives the signal. If the incoming); signal of still loneerduration, say five seconds, the circuit controller causes the. energization of relays H and T. relay H being connected to contact point 5. Relay H closes at contact 36 the circuit of lamp 5. so that the signal is received by the operator at the through position. It is thus apparent that by the zmparatus (it this invention; any number of ditl erent opcrators positions may he selectively signaled, according to the length of the ring, coming in on the line.

The apparatus of Fig. 1 is arranged also to send ringing current of various durations over the line for the purpose of signaling selectively to other operators positions at other otlices associated with the line.

For causing a ring ot', say, one second duration, the operator inserts the plus of her cord into one of the jacks 1, 3 or a so that current from the s eeve battery 42 flows through a resistance 1:3 into the sleeve circuit comprising; relays J and L. Relav l operates and sets the busy signals as described hereinbefore. The operator now depresses the ringing key 38 associated with the cord circuit, which key causes current from a battery 40 in series with a resistance 41 to flow through contact 44 into the sleeve circuit. This battery is of higher potential than batterry i2, so that more current flows through the sleeve circuit, enough to operate 'marginal relay L, which closes contact if) and causes the energization of relays M and 0. Relay 0 operates its contacts and causes ringing current to enter line Z from a source associated with the back contacts of a relay V, the frequency of this source being generally 16 cycles, although any other suitable frequency may be employed. It should be noted that the energiz'ation of relay 0 also acts to prevent the flow of ringing current into line Z from a source 99 associated with the contacts of the ringing key 38, this source being provided so that the cord may be used with the commonly employedtype of line jacks not equipped with the selective sig nalingfeatures of this invention. The relay M locks up through its contact 50 which is connected in series with the winding: of a relay N through contact 49 of a relay S to a battery 4-8. Relay N is thus energized and closes contact 51 so that the circuit of relay 0 remains complete whenurelay L is decnergized .as the operator releases the ringing key38. The relay N closes also contact 52,1soqthat current flows troinbattery through contact 52, wire 60, through the winding of relay P, which by closing, its frontcQntacts reverses the circuit of the mo tor D traced hereinbefore. The closure of contact 52 also causes the circuit controller Y to begin operating, current being furnished to the armature of motor D and to the winding 9, through contact 52 of relay N, Wire 60, back contact 14 of relay 0, contact 15 of. relay I, conductors 16 L7 and 18, through winding 9 and motor D in parallel. The circuit controller Y is thus caused to commence operating when the ringing current begins to flow into the line, the direction of rotation, however, being counterclockwise because motor D is operating in the reverse direction. Relay N causes, furthermore, the connection of relays V and S in parallel tothe' inner contact points of the circuit controller, the: connection being from battery 53 and, relay V, and from battery 48 and relay S, in parallel, through front contact 22 of relay N, wire 24: to the inside contact points of the circuit controller; Relay M, moreover, when it became energized, applied the ground on the armature of relay Q; to the contact point 1 of the controller Y, through the front contact 63 of there'lay M, so that the moment the brush 10] on the contact arm 8 bridges the; contact points-l i. e. one second after ringing current was first applied to line Z, relays S and V be come energized. Relay. V opens its back contacts, thus stopping further flow of the ringing current into line Z. [Relay S opens contact. 49 and causes thus the deenergiza tion of relays and N, which relays stop the operation of controller Y and restore the.

relays .O and P to their normal positions A. signalingiinpulse of one second duration is thus sent over the conductors of line Z.

In case the operator holds the ringing key 38 depressed for more than one second, relay L is still energized at the time when the circult ofrelay S is closed by controller Y. Re

lays O and M in this case remain energized through contact 45 of relay L and relay S is held closed by a locking circuit which extends from battery -18 through the windin get relay S, through contact 64 of relay S and contact 45 of relay L to ground. Relay V remains energized throughfthe same contacts. The, re-energization of relay N is thus prevented by relay S; the reapplica-' tion of ringing current to the line from the source associated with the contacts of relay V is obviated by relay V, and the flow of current into the line from the source 99 is prevented by relay 0. In this manner-I am enabled to make the duration of the signaling impulses independent of the length of time the ringing key is depressed.

For the purpose of applying ringing currentof different duration to the line, say for three seconds,'the operator does not depress key 38, but throws key 39 to the left. This key is arranged to operate both left and right contact springs when thrown to the left, but only the right contact springs when thrown to the right. The operation of the key causes the current fromubattery 40 to flow into the sleeve circuit through contact 8.1 of key 39*andcontact 44 of key 88, this current causing the operation of marginal relay L which, as hereinbeforeexplained, brings about. the operation of relays M, N

and 0 so that theringing current commences to flow over the line and the circuit controller Y begins to: operate; Key 39 also occatact 68', wire 69, contact 70,, conductor 71 and contact ofkey 38 through the tip contacts of the plug and jack into conductor 2,, fromwhich conductor it flows through wire 72, contact 73 ofrelay L, throughthe windings of relays Q and R in series. Relay R is marginal and does not operate with the strength ofcur'rent presently flowing there through. Relay Q, however, closes its front contact, and connects the ground on its armature through the back contact of relay R to the outside contact point 3 of circuit controller Y. The operation of the other apparatus is the same as described herein,- before for the one second ring, except of course,.'that because of the energization of relay Q, there is no ground connected to con tact 1 of the circuit controller. When, therefore, the brush 10 reaches contact 1 after an interval of one second, relays V and S; fail to respond, so that ringing currentcontinues. to flow at the end'oi three (ill seconds the brush reaches contacts 3, at which time relays V and S are energized and stop further flow of the ringing current into line Z, as explained hereinbefore.

WVhen the operator desires to impress current of still different duration on line Z, say five seconds, she throws key 39 to the right so that current from battery 40 enters the sleeve circuit as before, and current from battery flows through resistance 66, contact 68, wire 69, contact 70, wire 71 and contact of key 38 into the tip side of the cord and through relays and R as before. Belay R is now furnished with suflicient current to close its front contacts, the current in the circuit being of a larger value than before because the resistance 67 is not in circuit. Relay R causes the ground on the armature of relay Q to be connected to the contact point 5 of the controller Y. The operation of the other apparatus is the same as hereinbetore described, the relays V and S being energized to stop the flow of ringing current at the end of a period of five seconds.

In a modification of the invention I employ instead of the selective ringing keys in the cord circuit, separate jacks at each operators position for sending the ringing currents of diilerent durations over the line. This modification is illustrated in Fig. 2, in which A,, B and C designate the jacks at one of the operators positions, for example, the inward position. The cord circuit used with this arrangement is similar to the one illustrated in Fig. 1, except, of course, that it is not provided with the selective key 39. Each of the above jacks is provided with a sleeve circuit, which comprises a relay X X or X respectively, in series with relays J and L. When the operator wishes to send a ring over the line of, say, one second duration, she associates the plug of her'cord with the jack A so that current from battery 42 in the cord flows through relays X,, J and L, thus energizing relays X,, J and L, setting the busy signals which are not shown in this figure. Relay L, being marginal, does not close its contact until the operator depresses ringing key 38, thus associating battery 40 with the sleeve circuit, similarly as in the arrangement of Fig. 1. Relay L connects ground to the winding of relay 0, and thus starts the ringing impulse over line Z. Relay L also connects ground to the winding of relay M, so that the same is energized by current from a battery 90, through the back contact 96 of relay S. Relay M closes a locking circuit through contact 93 and relay 0 is maintained closed by the same contact, so that the operator may release ringing key 38. The relay L being thus restored to its normal unenergized condition. The circuit controller Y has in the meantime commenced operating, its circuit having been closed through contact 94 of relay M. The relays S and V are connected in parallel through the contact 95 of relay M to the inside contact points of the said controller Y so that both of these relays are energized when, after a period of one second, the contact brush 10 of the controller bridges the contact points 1, the outside contact point being connected to ground through the contact of the relay X Relays S and V are, therefore, energized one second after ringing current begins to flow over the line, and relay V, by opening its back contacts, prevents the further flow of the ringing current into the line conductors. Relay S causes the deenergization of relay M by opening its back contact 96 and relay M opens the circuits of relay O and of circuit controller Y, thus restoring the apparatus to its normal position.

In case the operator holds the ringing key 38 depressed for a period of time longer than one second, relay L remains energized at the time when relays S and V are operated. In this case relay S is held up through a locking circuit, which extends through the contact of 97 of relay S and through the contact of relay L; relay V remains closed through a circuit which extends through the same contacts and relay O remains closed through the contact of relay L. These relays thus operate to prevent the further application of ringing current to the line no matter how long the operator holds the key depressed.

For the purpose of sending a ring of diff-erent duration over line Z, say three seconds, the operator associates her cord with the jack B instead of A, and thus occasions the energization of relay X instead of relay X,. Relay connects ground to the outside contact point 3 so that relays S and V do not operate until three seconds after the flow of the ringing current has begun. Finally, if the operator desires to send a five second ring over the line she associates the plug of her cord with jack 0, so that relay X becomes energized. and connects ground to contact point 5. Relays S and V thus cause the discontinuation of the ring ing current after a period of five seconds. Any other number of signals of different duration may thus be sent over the line by use of additional jacks. The signal receiving apparatus associated with the above described type of sending apparatus may be similar to the receiving apparatus described with reference to Fig. 1 and has not been shown in this view to prevent unnecessary complications.

In still another form of embodiment of the invention, I associate the time element circuit controller with the operators cord circuit, as shown in Fig. 3. In this form of the apparatus the operator is provided, as before, with the regular ringing key 38 and masses in addition, with a master ringing key 100, comprising contacts and 100 which key maybe commonto all the Cords of the same position; In using this arrangement the operator associates the plug of the cord with the jack of the line Z and depresses the ringing key38. This causes ringing current from a a source associated with the arma tures of asrelay 1101, to flow over the tip and ringcontaots of key 38 into the conductors oat-the tclephonoline. h operation of the ringingwkcy connects also the battery 102 with themotor Dtand the magnetizing Wlll(l-' int; 8 of thearmof the circuit controller Y, thus causing the sameto commence operating. Battery 1.0.2 is soconncctcd to the inside contaotpoints ofthe control cn S0 that when the contactbrush lO oithe controller bridges, ,aftera period of one second, the contact point 1 current from battery 102 flows through these contact points and through theback contact of-relays 112. and 103 in series througlrthe windings of relays 101 and 104, so that both of these relays are energized and close their front conacts. Relay 101 thuscd sconnec e source ofts gnaling urren r m t e e ephone line, and relay 1% clos he circuit of the pilo signal lamp 105,1yl1ichthusseryes to indi cats .to heoperator that a ringing impuls of n s n duratio ha been sent out over-the line and that she may release the ringing key. Relay 101 sei vcsalsoto open the circuit of the. controller Y, so that ,the apparatus is restored to its normal condition. v .7 a i In case the op t r d sires to send out a ringing impulse of longer du a ion, say three seconds, she depresses key 38 and op crates also the master ringing keylOO, in Sacha manner that the contact 100 is closed. The operation of key-88 causes, as before, the commencement-of the flow of ringing current intoithe line conductors andtbc beginv ning of the operati nof the circuit contmllenY. The closure ofcontact 100% causes current toflowtrom battery 103, through relay 103 and lamp 107 in parallel, through contact 1100 to ground so that the lamp ltl'liislighted andirelay 103 closesits front contacts. The operator may now release the master key, for relay 103 retains itself energized through. a locking circuit extending through contact 109 ofre1ay103 and through the back contact of relay 104E. Lamp107 is supplied With current through the same circuit and serves to indicate that a three second signal is being applied to the line. The relay 103 has in the meantime disconnected ;relays }10 l and 10 1 from the contact point l andconnectcd thesame through the ,front contact ofrelay 103 to contact point 3?. When, therefore, the controller bridges cQnt WtSaP nolaysglQl and 104 failto operate, and, in fact, do not respond until tie brush 10 bridges contacts 3 thr e se onds after the beginn ng f t ling? Relays 101 and met-then operate, similarly as described hereinbefore, to discontinue the ring and to light the pilot lamp 105 to signal to the operator that she may release the ring ing ,key 38. Relays 101 and 10,4 also open the circuits of controller Y, relay l03and lamp 107, thus restoring the apparatus to its normal position. 1 c s In case the operator desires to. send va ring of five seconds duration over the line, she depresseskey 38as before, and operates contact 1-00 of the master ringing key. Battery 106 now energizes relay 112' and 1am 110, the cir uits of which remain closed through the contact 1110f relay 112, when the operator releases the master key. Relay 112 causes the connection of relays 101 and 104; to the contact points 5 of controller Y, so that these relays operate after a signal of live seconds duration. The circuitsof the present modification may be u in conjunction with the receiving circuit arrangement shown in Fig. Lorin conjunction With any other-suitable receiving arrangement. s

Although all the above described forms of embodiment, of the invention are ar anged. for use with a sy tem mp oying signaling currentsof only three different durations, it is readily understood that the apparatusmay be arranged for usewith an,

other desirable number and lengths of periods. Many other changes and modifies tions may be made therein'yvithin thescope of the following claims. without departing 7 from the. spirit and s ope of the inven o What I claim is:

'1. In combination, acontroller, an actuating circuit therefor, another circuit actuatcd thereby after an interyalof time determined by the duration of current in the actuating c1rcuit,meansfor causing the commencement of the operation of sa d controller, and means assoc1ated with said actu:

ated circuit for causing the oessationof the 'yvith said circuit,pa contact, a circuit mcom troller for operating said contact after an interval of time determined by the duration of current in the actuating circuit, a motor driving said controller and actuated by current in said circuit, means for causing the said controller to begin its operation when said source is associated with said circuit, and a device associated with said contact for causing the disconnection of said source from said circuit when said contact is operated by said controller.

l. In combination, a circuit, a source of current therefor, a device for associating said source with said circuit, a plurality of contacts, a controller for operating said con tacts successively after predetermined intervals of time, a motor to drive said controller, and selective means associated with said contacts to cause said source to be removed from said circuit after one of said predetermined intervals of time, and to stop said motor and disengage it from said controller.

5. In combination, a telephone line, a ring ing key, a source of ringing current and means actuated by said key for applying said source to said line for any one of several predetermined periods of time, and means for selectively determining one of those periods.

6. In combination, a telephone line, a ringing key, a source of ringing current, means actuated by said key for applying said source to said line, selective means for determining the length of time said source is applied and means for rendering the length of time during which said source is associated with the line unaii'ected by the time during which said key is operated.

7. In combination, a telephone line, a plurality of ringing keys, a source of ringing current, and a single controller selectively actuated by said keys for applying said source to said line for selected predetermined intervals of" time, and for restoring said controller to its initial condition at the end of each such interval of time.

8. In combination, a telephone line, a source of ringing current, a cord circuit, a plurality of ringing keys associated therewith, means actuated by said keys for applying said source to said line, means for causing the disconnection of said source from said line after predetermined intervals of time, circuits responsive to the strength of current therein for selectively governing said last mentioned means, and means controlled by said keys for governing the strength of current in said circuits.

9. In a telephone system, a line, a plurality of operators positions associated therewith, and a single controller for selectively signaling to said operators positions according to the length of a ring over said line, and means to restore said controller actuated automatically at the end of each such ring over the line.

10. In combination, a circuit, a circuit controller responsive to the duration of current in said circuit, a motor to drive said controller, devices associated with said controller and selectively operated thereby, according to the duration of current in said 011'- cuit, and means to disengage said motor from said controller in accordance with the selective operation of said devices.

11. In combination, a circuit, a relay governed by current in said circuit, a circuit controlling device, means for causing the commencement of the operation 01 said device when said relay is energized, means for causing the cessation of the operation of said device when said relay is deenergized, contacts governed by said controller and operated selectively according to the length of time during which said controller is caused to operate, signal circuits associated with said contacts, a motor for said controller and means to stop the motor and disengage the controller therefrom upon such cessation of operation.

12. In combination, a circuit, a relay responsive to currents in said circuits, a circuit controlling device, means for causing said controlling device to operate while said relay is operated, contacts governed by-said controller and operated successively thereby after predetermined intervals of time, circuits associated with said contacts, means associated with said circuits for causing cessation of the operation of said controller when said relay ceases to operate, signal devices associated with said contacts and selectively operated thereby, a motor for said controller and means to stop the motor and disengage the cont roller therefrom upon such cessation of operation.

13. In a telephone system, a line, means for sending ringing current over said line, busy signals and operators signals associated with the line, means for causing the response of the busy signals at the commencement of a flow of ringing current and means for causing the response of an operators signal at the end of such flow.

i i. In combination, a circuit, a single controller associated with said circuit for causing flow of current therein of selectively predetermined duration, and means for indicating the cessation of flow of said current, and for automatically restoring the controller to its initial position.

15. In combination, a telephone line, a ringing key, means associated with said key for causing a flow of ringing current of selectively predetermined duration over said line, and a device for indicating the completion of said flow of ringing current.

16. In a telephone system, a line, a single circuit controller, an operators signal, means for causing said controller to actuate said ringing key, a source of ringing current and means governed by said controller upon an initial operation of said key for associating said source With said line for a predetermined period of time.

17. In combination, a telephone line, a controller, means operated. by said controller selectively in response to incoming ringing current of predetermined duration, and means selectively operated to cause said controller to put ringing current of predetermined duration on the line.

18. In combination, a telephone line, a controller means operated by said controller selectively by movement one Way from normal position in response toincoming ringing current of predetermined duration, and means selectively operated to cause said controller by movement the opposite Way to put ringing current of predetermined duration on the line.

In testimony whereof, I have signed my name to this specification this 9th day of October 1919.

JOHN F. TOOMEY. 

